### Home > A2C > Chapter 12 > Lesson 12.1.4 > Problem12-64

12-64.

Write each series in sigma notation and find the sum or an expression for the sum.

1. $47 + 34 + 21 + … + \left(−83\right)$

What is the expression for the sequence?

How many terms are there in the series?

One possible answer:

$\sum_{k = 1}^{11}(60-13k)=-198$

1. $3+10 + 17 + … + \left(7n − 4\right)$

Instead of going up to a specific term, this series sums up the first n terms of the sequence given in parentheses.